By way of contrast,  statutory law creates law with the successful statutes of a legislative body and regulatory law utilizes requirements and obligations handed down by members of the executive branch to form law.  Consitutional law predicates its laws upon the articles of the Constitution.

A governing principle of common law is stare decisis which in short means that if the components of a case are materially the same as a previously decided case then a similar result must be reached.

In the U.S. the Supreme Court, the only court expressly created by the Constitution, is a common law court by implication of Article 3 of the Constitution.  The Supreme Court uses common law to adjudicate the legal implications of statutory and regulatory law and the application of and implications of Constitutional law.

The term comes from English laws that were considered common among different districts over which itinerent judges presided.  These laws were not statutory in nature but the citizens of the several districts held them to be universally understood.   These common laws are referred to as having authority to review royal power in the Magna Carta by the term “. . . except by the lawful judgement of his peers or by the law of the land.” (emphasis mine)